It's a mistake to focus on the possible answer from the NCAA (assuming there was even a question) without knowing the question.
If I call someone with the NCAA and say, "Hey, we're running a last chance meet over here and we want to add a race at the end so some teams can try to qualify in the 4x400. Is that OK?"
They say, "Sure, you can add a race to the meet. It's your meet." Then they hang up, wondering why you even called to ask that strange question.
Then the NCAA learns what really happened. The race was hours later, after the meet ended and everyone had left the facility, and only the host team ran.
Does the supposed response qualify as "approval to do this"?
No, it does not.
We don't know that the NCAA was really contacted at all, but even if it was we need to know the question as much as the answer.
I doubt the question was, "Hey, we ran a meet today and every team has left the building and gone home. Can we run a time trial for just the host team, five hours later, and doctor the event schedule to look like this was an official event?"
